1. Field of the Invention
The present invention relates to a manifold reactor to be mounted in an internal combustion engine for purifying exhaust gases and, more particularly, a structure for a multi-walled manifold reactor including outer and inner cores.
2. Description of the Prior Art
The manifold reactor is a device which is mounted in an internal combustion engine closely adjacent the exhaust ports thereof as a substitute for an ordinary exhaust manifold for the purpose of purifying exhaust gases from the engine by utilizing the heat owned by the exhaust gases themselves so as to recombust harmful uncombusted components such as HC and CO contained in the exhaust gases by high temperature oxidization effected in a reactor chamber defined therein. Conventionally, the manifold reactor has generally a double or triple walled structure composed of outer and inner cores or the like in order to obtain better heat insulation for the reactor chamber, wherein the spaces defined between the outer and inner cores is filled with a layer of a solid heat insulating material so that a more improved heat insulation of the reactor chamber is obtained. However, in spite of these complicated multi-layered structures for the manifold reactor, when the engine starts from a low temperature condition with the inner core which defines the reactor chamber being also in a low temperature condition, sufficient oxidizing reaction is not effected in the reactor chamber. This problem becomes more serious in a counter flow type engine wherein a riser portion of the intake manifold is heated by the exhaust gases existing in the reactor chamber because, in this case, the temperature of the exhaust gases further lowers due to a loss of heat caused by heating the riser portion. Thus, there is a problem that even if a relatively massive heat insulation has been applied to the reactor chamber, sufficient oxidizing reaction does not take place in the reactor chamber.